{"id":441389,"date":"2026-09-16T13:56:19","date_gmt":"2026-09-16T17:56:20","guid":{"rendered":"https:\/\/alpha.pewresearch.org\/pewresearch-org\/?p=441389"},"modified":"2026-09-17T10:54:11","modified_gmt":"2026-09-17T14:54:11","slug":"3-ways-to-correct-a-polls-political-balance-party-affiliation-past-vote-and-voter-file-information","status":"publish","type":"post","link":"https:\/\/alpha.pewresearch.org\/pewresearch-org\/methods\/2026\/09\/16\/3-ways-to-correct-a-polls-political-balance-party-affiliation-past-vote-and-voter-file-information\/","title":{"rendered":"3 ways to correct a poll\u2019s political balance: Party affiliation, past vote and voter file information"},"content":{"rendered":"\n
About this research<\/summary>\n

This report explains political weighting<\/em> \u2013 adjusting a survey to reflect the political composition of the United States as accurately as possible.<\/p>\n\n\n\n

Why did we do this?<\/h4>\n\n\n\n

Pew Research Center does research to help the public, media and decision-makers understand important topics. In our surveys of the U.S. public, we regularly adjust, or \u201cweight,\u201d how much we emphasize certain groups\u2019 responses depending on how likely they are to participate, among other factors.<\/p>\n\n\n\n

This report examines best practices for weighting by political party affiliation and voting choice, particularly in the context of survey panels. It adds to the Center\u2019s extensive body of work on survey research methods<\/a>. Learn more about Pew Research Center<\/a>.<\/p>\n\n\n\n

How did we do this?<\/h4>\n\n\n\n

We drew on results from Pew Research Center surveys, as well as studies conducted by other researchers.<\/p>\n<\/details>\n\n\n\n

Pollsters vary in how they weight their survey samples on political characteristics, if at all. Their choices tend to be informed by factors such as the population being surveyed and the sample source (e.g., a list of all addresses in the United States or a list of registered voters), the focus of the poll (preelection standings or key issues), and geographic level (national, state or something else). No one approach is clearly superior in all contexts.<\/strong><\/p>\n\n\n\n

This section describes three ways to adjust a poll\u2019s political balance with weighting. Some polls use more than one of these adjustments. They\u2019re not mutually exclusive.<\/p>\n\n\n\n

(This is part of a larger Pew Research Center report about political weighting \u2013 adjusting a survey to reflect the political composition of the U.S. as accurately as possible. For an overview and the report\u2019s key takeaways, read \u201cWeighting Polls on Party Affiliation and Past Vote<\/a>.\u201d)<\/p>\n\n\n\n

Weighting on self-reported party affiliation<\/h4>\n\n\n\n

How it generally works:<\/em> Respondents indicate whether they consider themselves a Republican, Democrat or neither (and whether they lean to either party). After fielding, the pollster aligns the share of Republicans in the survey to match the share nationwide. They do this for Democrats as well. The result is that the survey accurately matches the benchmark shares of Republicans and Democrats.<\/p>\n\n\n\n

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In practice, this can be tricky because none of the large federal surveys that pollsters use to obtain weighting targets measure party affiliation. Pollsters who survey U.S. adults (not just voters) sometimes use Pew Research Center\u2019s National Public Opinion Reference Survey (NPORS<\/a>) or their own address-based survey<\/a> for a party affiliation benchmark.<\/p>\n\n\n\n